Unit 5 Cellular & Organismal Reproduction

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Unit 5: Cellular & Organismal Reproduction
Topic 1: The Cell Cycle
Cell reproduction
• How do cells reproduce?
They divide into two cells!
First they copy all their parts (DNA, organelles, ribosomes)
• When does a cell reproduce?
When a multicellular organism is growing or needs to
replace dead or damaged cells (mitosis)
To make gametes for sexual reproduction in eukaryotes
(meiosis)
When a single-celled organism reproduces asexually
(mitosis or binary fission)
Some Definitions
• Parent Cell
• Daughter Cell
• Sexual
Reproduction
– Variation
• Asexual
Reproduction
3
Asexual reproduction in bacteria
(binary fission)
Figure 8.3A, p127
Binary
Fission
4
Other forms of asexual reproduction
•
•
•
•
Budding
Fragmentation
Regeneration
Advantages:
– Don’t need to
search for a mate
– Can reproduce if
damaged
• Disadvantage:
– No recombination
of genetic material
Chromatin
6
7
Fun facts: number of chromosomes in a variety of organisms
Species
Humans
Kangaroo
Cat
Cow
Dog
Turkey
Algae
Shrimp
Ophioglossum reticulatum
(fern)
# chromosomes
46
12
38
60
78
82
148
254
~1200! (highest
UNreplicated
Chromosome
Replicated
Chromosome
Sister
Chromatids
UNreplicated
Chromosomes
Figure 8.4, p128
10
Chromosome Anatomy
11
Homologous chromosomes
• Each chromosome has a
homologue, or a
chromosome that carries
the same type of
information as another
chromosome
• The chromosomes may
have different versions
of the genes but the
genes code for the same
type of information
12
Cell cycle
Figure 8.5, p129
13
Mitosis inquiry
Cell cycle
Figure 8.5, p129
15
The stages of mitotic cell division in an animal cell:
G2 phase; prophase; prometaphase
Figure 8.6, p130
16
The stages of mitotic cell division in an animal cell:
metaphase; anaphase; telophase and cytokinesis.
Figure 8.6, p131
17
Mitosis
18
Mitosis in an onion root
19
Cytokinesis in animal and plant cells
Figure 8.7, p132
20
Cell turnover
• The length of a cell cycle
depends on the type of
cell and its function in
the body.
• Some cells never divide
after the first few months
of life: brain, nerves
• Some cells never divide
at all: red blood cells
• Some divide every 20
hours or so: cells of
organ linings and skin
cells
Chromosomes
23
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